function findChild(arr) {
    let result = [];
    let temp = [];
    let dep = 0;
    function dfs(temp, dep) {
        result.push(temp)
        for (let i = dep; i < arr.length; i++) {
            temp.push(arr[i])
            dfs(temp.slice(), i + 1)
            temp.pop()
        }
    }
    dfs(temp, dep)
    return result
}

console.log(findChild([1, 2, 3]))